As of 6/7/16, according to the Stack Exchange Meta rules on "Promotion", specifically "How to not be a spammer" (emphasis not mine):
The community here tends to vote down overt self-promotion and flag it as spam. Post good, relevant answers, and if some (but not all) happen to be about your product or website, that’s okay. However, you must disclose your affiliation in your answers.
Although he's on topic, he is not disclosing his affiliation with the website or tutorials, so he is breaking the rules. So it's technically spam, or at least spamm-able.
(As far as I know, every Stack Exchange site has this same exact page about "How to not be a spammer"...and all of the rules for the most part)